Golf ball

ABSTRACT

The object of the present invention is to provide a golf ball having a lasting scent. The golf ball of the present invention is a golf ball comprises a paint film on a surface of the golf ball body, wherein the paint film comprises a microcapsule encapsulating a perfume material. Employment of such a structure inhibits a release of the perfume material component in the paint film during storage of a golf ball, since it is included in the microcapsule. When in use, a film material of the microcapsule is gradually broken by hitting the golf ball, so that the perfume material included in the capsule is gradually released.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a golf ball, more particularly to a painted golf ball provided with a paint film on a surface of a golf ball body.

2. Description of the Related Art

Flying performance is, without saying, an important feature of a golf ball. Further, a golf ball is required to have unique characteristics; for example, such efforts as imparting a unique appearance to a golf ball and adding a scent to a golf ball are made. Examples of imparting a unique appearance to a golf ball include Japanese Published Unexamined patent Application Nos. 2005-52510 and 2000-254251. Each of Japanese Published Unexamined Patent Application Nos. 2005-52510 and 2000-254251 proposes a golf ball having a color flop effect, i.e., a change of a color tone depending on the angle from which to look by blending a liquid crystal polymer in a cover layer and a paint film layer. Examples of a golf ball with a scent added include Japanese Unexamined Patent Application Nos. H4-49984 and 2005-279227. Japanese Unexamined Patent Application No. H4-49984 discloses a golf ball into a surface of which a scent or a taste repelling crows is immersed. Japanese Unexamined Patent Application No. 2005-279227 discloses a golf ball having a core comprising a scented felt, cork and the like.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a golf ball keeping a lasting scent.

The golf ball of the present invention that has accomplished the above object is a golf ball comprises a paint film on a surface of the golf ball body, wherein the paint film comprises a microcapsule encapsulating a perfume material. Employment of the structure in the golf ball inhibits a perfume material component in the paint film from being vaporized while the golf ball is stored since the perfume material component is included in the microcapsule, and when in use, the film material in the microcapsule is gradually broken by hitting the golf ball, so that the perfume material included therein is gradually released. As a result, the golf ball of the present invention keeps a long-lasting scent.

The present invention provides a golf ball having a lasting scent.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The golf ball of the present invention is a golf ball provided with a paint film on a body thereof, wherein the paint film comprises a microcapsule encapsulating a perfume material.

First, the microcapsule encapsulating a perfume material will be explained. A microcapsule encapsulating a perfume material is not particularly limited as long as the perfume material as a core material is included in the film material, and a preferable example is one in which the film material is destroyed and the perfume material is released by an impact or a shear when hitting the golf ball.

The perfume material can be suitably selected depending on a desired scent, and it is preferably at least one kind selected from the group consisting of a terpene, an ester compound, an aromatic compound, an ether compound, an aldehyde compound, an alcohol compound, a ketone compound, a lactone compound and a nitrogen-containing compound.

Examples of a perfume material giving exhilaration and a cooling sensation include scents of mint and a spice (herb), which have an effect of refreshing the mood of a player or keeping a player focused. Examples of the perfume material giving exhilaration and a cooling sensation include limonene (a terpene: a scent of lemon), menthol (an alcohol compound: a scent of mint), menthone (a ketone compound: a scent of mint), terpineol (an alcohol compound: a scent of lime), citral (an aldehyde compound: a scent of lemon), camphor (a ketone compound: a scent of mint), anethole (an ether compound: scents of fennel and the like), estragole (an ether compound: a scent of estragon), 1,8-cineol (an ether compound: scents of eucalyptus, sage and laurel), eugenol (an alcohol compound: scents of clove, pimento and the like), cummin aldehyde (an aldehyde compound: a scent of cummin), and cinnamyl aldehyde (an aldehyde compound: a scent of cinnamon).

Examples of a perfume material giving a therapeutic feeling include scents of fruits and flowers, which have an effect of calming one's feeling when feeling excited or feeling pressed. Examples of the perfume material giving the therapeutic feeling include cucumber alcohol (an alcohol compound: scents of melon and watermelon), aldehyde C-8 (an aldehyde compound: a scent of orange), cucumber aldehyde (an aldehyde compound: scents of melon and watermelon), vanillin (an aldehyde compound: a scent of vanilla), nootkatone (a ketone compound: a scent of grapefruit), raspberry ketone (a ketone compound: a scent of raspberry), ethyl caprate (an ester compound: scents of rum and brandy), allyl caproate (an ester compound: a scent of pineapple), isoamyl acetate (an ester compound: a scent of banana), ethyl acetate (an ester compound: scents of melon and grape), styrallyl acetate (an ester compound: a scent of grapefruit), hexyl acetate (an ester compound: scents of apple and pear), ethyl butyrate (an ester compound: a scent of pineapple), coconut aldehyde (a lactone compound: a scent of coconut), peach aldehyde (a lactone compound: a scent of peach), methyl anthranilate (a nitrogen-containing compound: a scent of grape), rose oxide (an ether compound: a scent of rose), geraniol (an alcohol compound: a scent of geranium), linalool (an alcohol compound: a scent of lavender), β-phenethyl alcohol (an alcohol compound: a scent of rose), cyclamen aldehyde (an aldehyde compound: a scent of lily of the valley), α-ionone (a ketone compound: a scent of violet), α-jasmone (a ketone compound: a scent of jasmine), and benzyl acetate (an ester compound: a scent of jasmine).

The film material of the microcapsule encapsulating the perfume material is not particularly limited as long as it is broken by an impact of hitting the golf ball or the shear caused by rubbing a surface of the golf ball, so that the perfume material is released. Such examples include a melamine resin, a polyurethane resin, gelatin, a polyethylene resin and an urea-formalin resin. Among them, a melamine resin is preferable as the film material of the capsule containing the perfume material because the melamine resin is high in airtightness, so that the perfume material component is inhibited from being released from the microcapsule while being stored.

The film material preferably contains a resin having a melting point of 110° C. or more, more preferably 120° C. or more, even more preferably 130° C. or more, even more preferably 200° C. or more. By containing a resin having a melting point of 110° C. or more, the film material is not melted, so the perfume material is inhibited from being released even if the golf ball is left in a trunk in summer.

The melting point of the film material of the microcapsule can be determined, for example, by 2910-Type differential scanning calorimeter available from TA Instruments. Japan.

A content of the microcapsule encapsulating the perfume material in the paint film is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, even more preferably 10 parts by mass or less relative to 100 parts by mass of the solid content constituting the paint film. If the content of the microcapsule encapsulating the perfume material is less than 0.5 parts by mass, there will be a shortage of active components of the perfume material so that it will be hard to keep a long-lasting scent. On the other hand, if the content of the microcapsule encapsulating the perfume material becomes more than 20 parts by mass, the content of the microcapsule encapsulating the perfume material relative to the solid content becomes too large, so that the paint film may become fragile and the adhesion thereof to the golf ball body may be lowered.

A number average particle diameter of the microcapsule encapsulating the perfume material is preferably 30 μm or less, more preferably 20 μm or less, even more preferably 10 μm or less. If the number average particle diameter becomes more than 30 μm, the microcapsule encapsulating the perfume material may clog in a spray gun for coating.

The number average particle diameter can be determined by Laser Scattering Particle Size Distribution Analyzer “LA-910” available from HORIBA, Ltd.

Specific examples of the microcapsule encapsulating the perfume material used in the present invention include Capsule Cologne A, Capsule Cologne B, Capsule Cologne C, Capsule Cologne D, and Capsule Cologne E available from Chemitech Inc.

The resin component of the paint film of the golf ball of the present invention is not particularly limited as long as it is a resin used as a component of a paint film of a golf ball. For example, an acrylic resin, an epoxy resin, an urethane resin, a polyester-based resin, a cellulose-based resin and the like may be used, and an after-mentioned two-component curing type urethane resin is preferably used. If the two-component curing type urethane resin is used as the resin component, a paint film which is excellent in wear-resistance and durability can be obtained.

The two-component curing type urethane resin is an urethane resin obtained by curing a base material by reacting the base material with a curing agent. Containing urethane polyol and a polyisocyanate as a curing agent Such examples include one obtained by curing a base material containing an isocyanate group terminated urethane prepolymer with a curing agent having active hydrogen, and one obtained by curing a base material containing a polyol component with polyisocyanate and a derivative thereof.

Particularly, it is a preferred embodiment of the present invention that the paint film comprises, as the resin component, a two-component curing type urethane resin obtained by curing a base material containing a polyol component with a curing agent such as polyisocyanate or a derivative thereof.

As the base material containing the polyol component, for example, a specific urethane polyol described below is preferably used. The urethane polyol is not particularly limited as long as it is a polyol having a urethane bond and at least two or more hydroxyl groups (preferably at a terminal thereof); for example, it is obtained by reacting polyol with polyisocyanate in such a proportion that the hydroxyl groups of the polyol component become in excess relative to isocyanate groups of the polyisocyanate by molar ratio.

The polyisocyanate constituting the urethane polyol is not particularly limited as long as it has two or more isocyanate groups. For example, an aromatic polyisocyanate such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate (TDI), 4,4′-diphenyl methane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-bitolylene-4,4′-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI); an alicyclic polyisocyanate or an aliphatic polyisocyanate such as 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI), hydrogenated xylylenediisocyanate (H₆XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI) or the like may be used; these may be used alone or as a mixture of two or more kinds. Among them, in view of weather resistance, a non-yellowing type polyisocyanate (TMXDI, XDI, HDI, H₆XDI, IPDI, H₁₂MDI, NBDI and the like) is preferably used. The polyisocyanate may be employed as a curing agent for curing the urethane polyol.

The polyol used for producing the urethane polyol is not particularly limited as long as it has a plurality of hydroxyl groups, and for example, a polyol having a low-molecular weight or a high molecular weight may be used. Examples of the polyol having a low-molecular weight include a diol such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and a triol such as glycerin, trimethylol propane, and hexanetriol. Examples of the polyol having a high molecular weight include a polyether polyol such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); a condensed polyester polyol such as polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA); a lactone polyester polyol such as poly-ε-caprolactone (PCL); a polycarbonate polyol such as polyhexamethylene carbonate; and an acrylic polyol. Among the polyols, a polyol having a weight average molecular weight of about 50 to 2,000, particularly about 100 to 1,000 is preferably used. These polyols may be used alone or as a mixture of two or more kinds.

A proportion of urethane bonds in the urethane polyol is preferably 0.1 mmol to 5 mmol in 1 g of the urethane polyol. The ratio of the urethane bonds is related to rigidity of the paint film to be formed; if it is less than 0.1 mmol/g, abrasion-resistance tends to be insufficient since a urethane bond concentration in the paint film to be formed is low, while if it is more than 5 mmol/g, the paint film tends to become too hard.

A weight average molecular weight of the urethane polyol is preferably 4,000 or more, more preferably 4,500 or more, and preferably less than 10,000, more preferably 9,000 or less. If it is less than 4,000, it takes a long time to dry, so that workability and productivity tend to be lowered. On the other hand, if the urethane polyol has a high molecular weight of 10,000 or more, the hydroxyl value of the urethane polyol becomes relatively small, so that an amount to be reacted after coating becomes small and thus adhesion to a base (golf ball body) tends to be lowered. Additionally, if a weight average molecular weight is 9,000 or less, a dense paint film which is small in lowering of adhesion even in a state of being wet in water can be formed.

The hydroxyl value (mgKOH/g) of the urethane polyol is preferably 15 or more, more preferably 73 or more, and preferably 130 or less, more preferably 120 or less. If it is less than 15 (mgKOH/g), an amount to be reacted with a curing agent becomes insufficient so that adhesion to a golf ball body tends to be lowered, while if it is more than 130 (mgKOH/g), a reaction with the curing agent takes a long time and it takes longer to dry, resulting in decrease in productivity.

The abovementioned urethane polyol is obtained, for example, by reacting the abovementioned polyol and polyisocyanate, for this reaction, a solvent and a catalyst publicly known in an urethanizing reaction (such as dibutyltin dilaurate) may be used. A percentage of the urethane bonds can be controlled by adjusting a molecular weight of the polyol which is to be a raw material, and a blending ratio of the polyol and the polyisocyanate.

As the base material containing the polyol component, an embodiment containing only the above specific urethane polyol is preferred; that is, essentially the above specific urethane polyol alone as the base material containing the polyol component is preferably used. However, other than the urethane polyol, a polyol which is compatible with urethane polyol and which is free of an urethane bond may be included. The polyol free of an urethane bond in this case is not particularly limited, and the abovementioned raw material polyol for a synthesis of urethane polyol may be used. Additionally, if the base material contains a polyol free of urethane bond, the content of the urethane polyol in the base material is preferably 50% by mass or more, more preferably 80% by mass or more. If the content of the urethane polyol in the base material is less than 50% by mass, the content of the urethane polyol becomes relatively small so that it will take longer to dry.

Besides the abovementioned resin components, the microcapsule encapsulating the perfume material and the like, the paint film of the golf ball of the present invention may further contain an additive which is included in a paint film of a conventional golf ball such as an ultraviolet absorber, an antioxidant, a light stabilizer, a fluorescent brightener, an antiblocking agent, and a pigment. Additionally, a preferred embodiment of the paint film of the golf ball according to the present invention includes a clear paint film substantially free of pigment.

The paint film may be provided on a surface of a golf ball body by coating a coating composition containing the resin component, the microcapsule encapsulating a perfume material, and further a solvent and the abovementioned additives as required followed by drying. A method for coating the paint composition is not particularly limited, and a conventionally known method may be employed. For example, an air spray gun, an electrostatic coating and the like may be used for coating on the golf ball body. Additionally, the surface of the golf ball body may be subjected to surface treatment such as cleaning or sandblast prior to the coating. Subsequently, the paint composition coated on the surface of the golf ball body is treated, for example, at the temperature of 30 to 60° C. for 1 to 6 hours to cure the paint composition, thereby the paint film is obtained.

The paint film may have, for example, a single layer structure or a multi layer structure, and a single layer structure is preferred. It is because, since the paint film of the present invention is excellent in adhesion to a golf ball, it can exert a sufficient performance with only a single layer structure as a paint film. A film thickness of the paint film is not particularly limited, but it is preferably 5 μm to 20 μm. If it is less than 5 μm, the performance of the paint film cannot be exerted sufficiently, while if it is more than 20 μm, a size of a dimple changes so that flying performance may be lowered.

The golf ball of the present invention has no limitation on its structure of the golf ball, and includes a one-piece golf ball, a two-piece golf ball, a multi-piece golf ball comprising at least three layers, and a wound-core golf ball. In a case of a golf ball having a cover such as a two-piece golf ball, a multi-piece golf ball, and a wound-core golf ball, resins such as an ionomer resin, a polyester resin, an urethane resin such as a thermoplastic urethane resin or a two-component curing type urethane resin and a polyamide resin may be used as the cover composition either alone or as a mixture of two or more kinds. Specifically, it is also a preferred embodiment to use, as the cover composition, an urethane resin such as a thermoplastic urethane resin or a two-component curing type urethane resin, an ionomer resin, or a mixture of an urethane resin and an ionomer resin in an amount of 50% by mass or more, more preferably 75% by mass or more, even more preferably 90% by mass or more. By increasing the content of the urethane resin or the ionomer resin, durability and shot feeling of the cover may be improved since the paint film comprising the microcapsule encapsulating the perfume material is also excellent in adhesion to these covers.

Examples of the ionomer resin constituting the cover include an ionomer resin which has been conventionally used as a cover composition of a golf ball, namely one prepared by neutralizing at least a part of carboxyl groups in a copolymer composed of ethylene and α, β-unsaturated carboxylic acid with a metal ion, or one prepared by neutralizing at least a part of carboxyl groups in a ternary copolymer composed of ethylene, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester with a metal ion.

Examples of the metal ion for neutralization include a monovalent metal ion such as a sodium ion, a potassium ion and a lithium ion; a bivalent metal ion such as a zinc ion, a calcium ion, a magnesium ion, a copper ion and a manganese ion; a trivalent metal ion such as an aluminum ion, a neodymium ion and the like. In particular, a zinc ion is preferred because it has a high bond strength of an aggregate of metal ions and the decrease in the mechanical strength based on dispersion of crosslinked diene rubber particles is small.

Specific examples of the ionomer resin include Himilan 1605 (commercial name of a sodium ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Himilan 1707 (commercial name of a sodium ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Himilan 1706 (commercial name of a zinc ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Himilan AM7315 (commercial name of a zinc ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Himilan AM7317 (commercial name of a zinc ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Himilan 1555 (commercial name of a sodium ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Himilan 1557 (commercial name of a zinc ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin) available from MITSUI-DUPONT POLYCHEMICAL. Iotek 8000 (commercial name of a sodium ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin) and Iotek 7010 (commercial name of a zinc ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin) available from Exxon Chemical; Surlyn 7930 (commercial name of a lithium ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), Surlyn 9945 (commercial name of a zinc ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin), and Surlyn 8945 (commercial name of a sodium ion-neutralized ethylene-methacrylic acid copolymer based ionomer resin) available from DUPONT CO.

Examples of the urethane resin constituting the cover include a two-component curing type urethane resin prepared by curing an isocyanate group terminated urethane prepolymer with an aromatic polyamine, or a thermoplastic urethane resin. The polyisocyanate component and the polyol component of the urethane resin are not particularly limited, and the same polyisocyanate and the polyol described as the urethane resin component of the paint film may be used. For example, an urethane resin using TDI as the isocyanate component and PTMG as the polyol component is preferred. The aromatic polyamine is not limited as long as it is a compound where two or more amino groups are directly or indirectly bonded to an aromatic ring. Such examples include a type in which an amino group directly bonds to an aromatic ring such as phenylenediamine, toluene diamine, and diethyltoluenediamine; a type in which an amino group bonds to an aromatic ring through a sulfide bond such as dimethylthiotoluenediamine; a type in which an amino group bonds to an aromatic ring through a lower alkylene group such as xylylenediamine; and 4,4′-diaminodiphenylmethane and a derivative thereof.

As the resin component constituting the cover of the present invention, it is also a preferred embodiment to use a thermoplastic elastomer in addition to the base resin such as the polyurethane and the ionomer resin. Specific examples of the thermoplastic elastomer include a thermoplastic polyamide elastomer having a commercial name of “PEBAX”, for example, “PEBAX 2533”, available from ARKEMA Inc, a thermoplastic polyester elastomer having a commercial name of “HYTREL”, for example, “HYTREL 3548” and “HYTREL 4047”, available from DU PONT-TORAY Co, a thermoplastic polyurethane elastomer having a commercial name of “ELASTOLLAN”, for example, “ELASTOLLAN ET880” available from BASF POLYURETHANE ELASTOMERS, and a thermoplastic polystyrene elastomer having a commercial name “Rabalon”, for example “Rabalon SR04” available from Mitsubishi Chemical Co.

The cover of the present invention may further contain a pigment component such as zinc oxide, titanium oxide, and a blue pigment; a gravity adjusting agent such as calcium carbonate and barium sulfate; a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material or a fluorescent brightener in addition to the above resin components, unless they impart any undesirable property to the cover.

A one-piece golf ball body or a core for two-piece golf ball and a multi-piece golf ball comprising at least three layers, for example, is preferably a molded body which is formed by heat-pressing a rubber composition. The rubber composition (hereinafter referred to as “rubber composition for the core” occasionally) preferably comprises a base rubber, a co-crosslinker, a crosslinking initiator, and a filler (a rubber core in a spherical shape). The core is not limited as long as it is composed at least of one layer, and may have either a single layer structure or a multi layer structure composed of at least two layers. The base rubber preferably includes a natural rubber and/or a synthetic rubber. Examples of the base rubber are a polybutadiene rubber, a natural rubber, a polyisoprene rubber, a styrene polybutadiene rubber, and an ethylene-propylene-diene rubber (EPDM). Among them, typically preferred is the high α-polybutadiene rubber having cis-1,4 bond in a proportion of 40% or more, more preferably 70% or more, even more preferably 90% or more in view of its superior repulsion property.

As the crosslinking initiator, an organic peroxide may be preferably used. Examples of the organic peroxide include an organic peroxide such as dicumyl peroxide, 1,1-bis (t-butylperoxy)-3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and di-t-butyl peroxide. Among them, dicumyl peroxide is preferably used. The organic peroxide is preferably blended in an amount of 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, and preferably 5 parts by mass or less, and more preferably 3 parts by mass or less based on 100 parts by mass of the base rubber. If it is less than 0.3 parts by mass, the core becomes so soft that resilience tends to be lowered, while if it is more than 5 parts by mass, the core becomes so hard that shot feeling will be lowered.

As the co-crosslinker, α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof may be used. A metal constituting the metal salt may include zinc, magnesium, calcium, aluminum, and sodium. Among them, zinc is preferable, because it can impart the higher repulsion property to the golf ball. Specific examples of the preferred α, β-unsaturated carboxylic acid or a metal salt thereof are acrylic acid, methacrylic acid, zinc acrylate, and zinc methacrylate.

In the case that the core has a two-layered structure comprising an inner core and an outer core and the thickness of the outer core is made thin, the zinc salt of α, β-unsaturated carboxylic acid providing the high resilience, especially zinc acrylate is preferable for the inner core layer, while the magnesium salt of α, β-unsaturated carboxylic acid providing the good mold-releasing property, especially magnesium methacrylate is preferable for the outer core layer.

The amount of the co-crosslinker to be blended in the rubber composition is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and preferably 55 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 48 parts by mass or less based on 100 parts by mass of the base rubber. If the content of the co-crosslinker is less than 10 parts by mass, the amount of the organic peroxide must be increased to provide the appropriate hardness, and thus the resilience tends to be lowered. On the other hand, if the content of the co-crosslinker is more than 55 parts by mass, the core becomes too hard and thus the shot feeling may be lowered.

As the filler, a filler conventionally formulated in the core of the golf ball can be used. The filler includes, for example, an inorganic salt such as zinc oxide, barium sulfate and calcium carbonate, a high gravity metal powder such as tungsten powder, and molybdenum powder and the mixture thereof. The content of the filler is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less based on 100 parts by mass of the base rubber. If the content is less than 0.5 parts by mass, it would be difficult to adjust the gravity, while if the content is more than 30 parts by mass, the ratio of the rubber included in the whole core becomes low and thus the resilience is lowered.

The rubber composition for the core may further contain an organic sulfur compound, an antioxidant, a peptizing agent and the like as required in addition to the base rubber, the co-crosslinker, the organic peroxide and the filler.

Examples of the organic sulfur compound include diphenyl disulfide, a monosubstitution such as bis(4-chlorophenyl) disulfide, bis(3-chlorophenyl) disulfide, bis (4-bromophenyl) disulfide, bis(3-bromophenyl) disulfide, bis (4-fluorophenyl) disulfide, bis(4-iodophenyl) disulfide, and bis(4-cyano phenyl) disulfide; disubstitution such as bis (2,5-dichlorophenyl) disulfide, bis(3,5-dichlorophenyl) disulfide, bis(2,6-dichlorophenyl) disulfide, bis (2,5-dibromophenyl) disulfide, bis(3,5-dibromophenyl) disulfide, bis(2-chloro-5-bromophenyl) disulfide, and bis (2-cyano-5-bromophenyl) disulfide; a trisubstitution such as bis(2,4,6-trichlorophenyl) disulfide, and bis (2-cyano-4-chloro-6-bromophenyl) disulfide; a tetra substitution such as bis(2,3,5,6-tetra chlorophenyl) disulfide; and a penta substitution such as bis (2,3,4,5,6-pentachlorophenyl) disulfide and bis (2,3,4,5,6-penta bromophenyl) disulfide. These diphenyl disulfides have some kind of effect on a state of vulcanization of a vulcanized rubber body to enhance resilience. Among them, diphenyl disulfide and bis(penta bromophenyl) disulfide are preferably used since a golf ball having high resilience can be obtained.

The amount of the antioxidant to be blended is preferably 0.1 part by mass or more and 1 part by mass or less relative to 100 parts by mass of the base rubber. The peptizing agent is preferably blended in an amount of 0.1 part by mass or more and 5 parts by mass or less relative to 100 parts by mass of the base rubber.

The core is formed by kneading the above rubber composition and press-molding it into the spherical body in the mold. The conditions for the press-molding should be determined depending on the rubber composition. The press-molding is preferably carried out for 10 to 40 minutes at the temperature of 130 to 180° C. under the pressure of 2.9 MPa to 11.8 MPa.

When preparing a multi-piece golf ball comprising at least three layers, an intermediate layer is formed between the core and the cover. As the intermediate layer, a same resin composition constituting the cover may be used. Such examples include a thermoplastic resin such as a polyurethane resin, an ionomer resin, nylon, and a polyethylene; a thermoplastic elastomer such as a polystyrene elastomer, a polyolefin elastomer, a polyurethane elastomer, and a polyester elastomer. Examples of the ionomer resin are one prepared by neutralizing at least a part of carboxyl groups in a copolymer composed of ethylene and α, β-unsaturated carboxylic acid with a metal ion, and one prepared by neutralizing at least a part of carboxyl groups in a terpolymer composed of ethylene, α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester with a metal ion. The intermediate layer may further include a gravity adjusting agent such as barium sulfate and tungsten, an antioxidant, a pigment and the like.

EXAMPLES

The following examples illustrate the present invention; however, these examples are intended to illustrate the invention and are not to be construed to limit the scope of the present invention. Many variations and modifications of such examples will exist without departing from the scope of the inventions. Such variations and modifications are intended to be within the scope of the invention.

[Evaluation Method]

(1) Impact Resistance

Each painted golf ball was hit 100 times repeatedly with W#1 (metal head) attached to a swing robot manufactured by TRUETEMPER CO, at the head speed of 45 m/sec. The impact-resistance was evaluated based on the following criteria.

E(Excellent): None of the paint film peeled off. G(Good): The area where the paint film peeled off was 3% or less with respect to the whole area of the paint film. F(Fair): The area where the paint film peeled off was more than 3% and 25% or less with respect to the whole area of the paint film. P(Poor): The area where the paint film peeled off was more than 25% with respect to the whole area of the paint film.

(2) Weather Resistance

Each of the golf balls was subjected to a weather-resistance test using Sunshine Super Long-life Weatherometer available from SUGA TEST INSTRUMENTS Co., LTD. in accordance with JIS D 0205 under following conditions: a temperature inside the tank at 63° C., humidity of 50%, and 12 minutes of rainfall out of the total of 60 minutes for 120 hours of radiation.

The color tone (L, a, b) of the golf ball before and after the weather resistance test was measured using CR-221, a color difference meter available from MINOLTA, and the color difference (ΔE) was calculated by the following formula:

ΔE=[(ΔL)²+(Δa)²+(Δb)²]^(1/2)

Herein, a higher value of color difference (ΔE) indicates a larger degree of discoloration.

(3) Drying Property

Golf balls immediately after coating were put in an oven at 40° C. to examine, and after the lapse of 120 minutes, the condition of the surface of the golf ball was examined by touching with finger.

G (Good): No smeary feeling remained, and the paint film had been cured. P(Poor): Smeary feeling remained.

(4) Airtightness of the Microcapsule

The perfume material component was encapsulated to prepare a microcapsule encapsulating the perfume material. After a lapse of 1 day, a leakage of a scent of the perfume material component was evaluated.

G(Good): Almost no scent of the perfume material component was detected. F(Fair): A little scent of the perfume material component was detected. P(Poor): A scent of the perfume material component was clearly detected.

(5) Scent

Each of the golf balls was hit by 10 golfers with W#1 (metal head), and a sensory test of the scent was carried out with respect to the golf balls retrieved.

Evaluation Criteria: E(Excellent): 9 or more golfers out of 10 golfers detected a scent. G(Good): 7 to 8 golfers out of 10 golfers detected a scent. F(Fair): 4 to 6 golfers out of 10 golfers detected a scent. P(Poor): Less than 4 golfers detected a scent.

(6) Persistence of the Scent

Each of the golf balls after having been left still in an oven at 50° C. for 1 month was hit by 10 golfers with W#1 (metal head), and a sensory test of the scent was carried out with respect to the golf balls retrieved.

Evaluation Criteria: E(Excellent): 9 or more golfers out of 10 golfers detected a scent. G(Good): 7 to 8 golfers out of 10 golfers detected a scent. F(Fair): 4 to 6 golfers out of 10 golfers detected a scent. P(Poor): Less than 4 golfers detected a scent.

[Production of Two-Piece Golf Ball]

(1) Preparation of the Core

The rubber composition shown in Table 1 was kneaded and pressed in upper and lower molds each having a spherical cavity at the heating condition of 170° C. for 20 minutes to obtain the core in a spherical shape having a diameter of 39.6 mm.

TABLE 1 Core formulation Blending quantity (parts by mass) Polybutadiene rubber 100 Zinc acrylate 25 Zinc oxide 10 Barium sulfate Appropriate amount*⁾ Diphenyl disulfide 0.5 Dicumyl peroxide 0.8 *⁾Formulation was adjusted depending on the cover composition in a manner that the mass of the golf ball became 45.4 g.

Notes on Table 1

Polybutadiene rubber: “BR730” available from JSR Zinc acrylate: “ZNDA-90S” available from NIHON JYORYU KOGYO Co., LTD. Zinc oxide: “Ginrei R” produced by Toho-Zinc Co. Barium sulfate: barium sulfate BD available from Sakai Chemical Industry Co. Ltd. Diphenyl disulfide: available from Sumitomo Seika Chemicals Company Limited Dicumyl peroxide: “Percumyl D” available from NOF Corporation

The barium sulfate was suitably added in a manner that a mass of a resultant golf ball became 45.4 g.

(2) Preparation of the Cover Composition

The materials shown in Table 2 were mixed using a twin-screw kneading extruder to obtain the cover composition in the form of pellet. The extrusion was conducted in the following conditions: screw diameter=45 mm, screw revolutions=200 rpm, screw L/D=35, and the cover composition was heated to from 200° C. to 260° C. at the die position of the extruder.

TABLE 2 Cover composition Formulation a b Surlyn 8945 45 45 Surlyn 9945 45 45 Rabalon SR04 10 10 Titanium dioxide 3 3 Ultramarine blue 0.1 0.1 Microcapsule containing perfume material A — 8.0 Slab hardness (Shore D) 60 60 Composition: parts by mass

Notes on Table 2 Surlyn 8945: An ionomer resin of a sodium ion-neutralized ethylene-methacrylic acid copolymer, available from DUPONT CO. Surlyn 9945: An ionomer resin of a zinc ion-neutralized ethylene-methacrylic acid copolymer, available from DUPONT CO. Rabalon SR04: A thermoplastic polystyrene elastomer available from Mitsubishi Chemical Co.

Microcapsule encapsulating perfume material A: “Capsule Cologne A” available from Chemitech Inc.: perfume material component: lavender, film material: melamine resin, average particle diameter: 2 μm

(3) Preparation of the Golf Ball Body

The cover composition thus prepared was directly injection-molded onto the core to form the cover, thereby obtaining the two-piece golf ball having a diameter of 42.7 mm. The upper and lower molds for forming the cover have a spherical cavity with dimples. The part of the dimples can serve as a hold pin which is retractable. When forming the golf ball body, the hold pins were protruded to hold the core, and the resin heated at 210° C. was charged into the mold held under the pressure of 80 tons for 0.3 seconds. After the cooling for 30 seconds, the molds were opened and then the golf ball body was discharged.

(4) Formation of the Paint Film Layer

As shown in Table 3, paint composition was prepared and was coated on a golf ball using an air gun followed by drying in an oven at 40° C. for 120 minutes to obtain a golf ball formed with a paint film having a thickness of 10 μm. The resultant golf ball was evaluated with respect to impact resistance, weather resistance drying property, scent, and persistence of the scent. The results are shown in Table 3.

TABLE 3 Golf ball No. No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 No. 10 No. 11 No. 12 No. 13 Cover composition a a a a a a a a a a a a b Film composition Urethane paint (solid resin 100 100 100 100 100 100 100 100 100 100 100 100 100 component) Microcapsule containing 0.3 0.6 8 18 23 — — — — — — — — perfume material A Microcapsule containing — — — — — 8 — — — — — — — perfume material B Microcapsule containing — — — — — — 8 — — — — — perfume material C Microcapsule containing — — — — — — — 8 — — — — — perfume material D Microcapsule containing — — — — — — — — 8 — — — — perfume material E Perfume OT-2354 — — — — — — — — — 8 — — — Perfume OT-2355 — — — — — — — — — — 8 — — Melting point of film 250 250 250 250 250 250 230 130 109 — — — 250 material (° C.) Airtightness G G G G G G G G F P P — G Evaluation Impact resistance E E E E G E E E E E E E E Weather resistance (ΔE) 2.3 2.3 2.3 2.4 2.4 2.3 2.3 2.3 2.3 2.5 2.4 2.3 2.3 Drying property G G G G G G G G G P P G G Scent G E E E E E E E E G G P F Persistence of scent G E E E E E E E E P P P P Composition: parts by mass

Notes on Table 3

Microcapsule encapsulating perfume material A: perfume material component: lavender, film material: melamine resin, average particle diameter: 2 μm Microcapsule encapsulating perfume material B: perfume material component: rose, film material: melamine resin, average particle diameter: 2 μm Microcapsule encapsulating perfume material C: perfume material component: lavender, film material: polyurethane resin, average particle diameter: 2 μm Microcapsule encapsulating perfume material D: perfume material component: lavender, film material: urea-formalin resin, average particle diameter: 2 μm Microcapsule encapsulating perfume material E: perfume material component: lavender, film material: polyethylene resin (low-density polyethylene 12), average particle diameter: 2 μm

Perfume OT-2354: liquid perfume material (lavender) available from T. HASEGAWA CO., LTD. Perfume OT-2355: liquid perfume material (rose) available from T. HASEGAWA CO., LTD.

In Table 3, the following paint was used as the urethane paint.

1) Base Material: Preparation of Urethane Polyol

116 parts by mass of PTMG650 (a polyoxytetramethylene glycol having a molecular weight of 650 available from Hodogaya Chemical Co., LTD.) and 16 parts by mass of 1,2,6-hexanetriol were dissolved into 120 parts by mass of the solvent (toluene and methylethyl ketone). The dibutyltin dilaurate was added in an amount of 0.1% by mass with respect to the total base material. While keeping this polyol at 80° C., 48 parts by mass of isophorone diisocyanate was slow-added into the polyol to obtain a urethane polyol having a solid content of 60 mass %, hydroxyl value of 87 mgKOH/g, and a molecular weight of 7850.

2) Curing agent: hexamethylene diisocyanate 3) Mixing ratio: NCO (curing agent)/OH (base material)=1.3 molar ratio.

Each of Golf balls No. 1 to No. 9 is a golf ball provided with a paint film on a surface of the golf ball body, wherein the paint film comprises a microcapsule encapsulating a perfume material. With respect to each of the golf balls, a scent inducing a therapeutic feeling was generated by hitting the golf ball. Each of the golf balls was also excellent in persistence of the scent. Comparing Golf ball No. 1 with Golf ball Nos. 2 to 4, the microcapsule encapsulating the perfume material was blended in Golf ball Nos. 2 to 4 in an amount of 0.6 parts by mass or more relative to 100 parts by mass of the solid content of the paint film so that the scent became more apt to be generated, and the persistence of the scent was improved, too. Further, by blending the microcapsule encapsulating the perfume material in an amount of 18 parts by mass or less relative to 100 parts by mass of the solid content of the paint film, impact resistance of the paint film was improved. Golf ball No. 9 was a case in which a melting point of the film material of the microcapsule was 109° C., wherein airtightness tended to be lowered.

Golf ball Nos. 10 and 11 are cases in which a liquid perfume material was used as a perfume material component, wherein the perfume material readily vaporized and the scent did not last. Golf ball No. 12 is a case in which the paint film did not contain a perfume material component, wherein no scent was found from the golf ball. Golf ball No. 13 is a case in which the microcapsule encapsulating a perfume material was blended in the cover, wherein little scent was found, and the persistence of the scent was low.

The present invention provides a golf ball which is high in persistence of scent.

This application is based on Japanese Patent application No. 2006-276918 filed on Oct. 10, 2006, the content of which is hereby incorporated by reference. 

1. A golf ball comprising a paint film on a surface of a golf ball body, wherein the paint film comprises a microcapsule encapsulating a perfume material.
 2. The golf ball according to claim 1, wherein the perfume material is at least one kind selected from the group consisting of a terpene, an ester compound, an aromatic compound, an ether compound, an aldehyde compound, an alcohol compound, a ketone compound, a lactone compound and a nitrogen-containing compound.
 3. The golf ball according to claim 1, wherein a film material of the microcapsule contains a resin having a melting point of 110° C. or more.
 4. The golf ball according to claim 1, wherein a film material of the microcapsule contains a resin having a melting point of 120° C. or more.
 5. The golf ball according to claim 1, wherein a film material of the microcapsule contains a resin having a melting point of 130° C. or more.
 6. The golf ball according to claim 1, wherein a film material of the microcapsule contains a resin having a melting point of 200° C. or more.
 7. The golf ball according to claim 1, wherein the film material of the microcapsule is at least one kind selected from the group consisting of a melamine resin, a polyurethane resin, a gelatin, a polyethylene resin and a urea-formalin resin.
 8. The golf ball according to claim 1, wherein the film material of the microcapsule is a melamine resin and the perfume material having a scent of lavender is included in the film material of the microcapsule.
 9. The golf ball according to claim 1, wherein the film material of the microcapsule is a melamine resin and the perfume material having a scent of rose is included in the film material of the microcapsule.
 10. The golf ball according to claim 1, wherein the film material of the microcapsule is polyurethane resin and the perfume material having a scent of lavender is included in the film material of the microcapsule.
 11. The golf ball according to claim 1, wherein the film material of the microcapsule is urea-formalin resin and the perfume material having a scent of lavender is included in the film material of the microcapsule.
 12. The golf ball according to claim 1, wherein the film material of the microcapsule is polyethylene resin and the perfume material having a scent of lavender is included in the film material of the microcapsule.
 13. The golf ball according to claim 1, wherein the microcapsule has a number average particle diameter of 10 μm or less.
 14. The golf ball according to claim 1, wherein the paint film contains 0.3 parts by mass to 25 parts by mass of microcapsule encapsulating a perfume material relative to 100 parts by mass of a solid content of the paint film.
 15. The golf ball according to claim 1, wherein the paint film contains 0.5 parts by mass to 20 parts by mass of microcapsule encapsulating a perfume material relative to 100 parts by mass of a solid content of the paint film.
 16. The golf ball according to claim 1, wherein the paint film obtained by curing a two-component curing type urethane resin.
 17. The golf ball according to claim 16, wherein the two-component curing type urethane resin comprises a base material containing a urethane polyol and a polyisocyanate as a curing agent. 